Sunday, July 12, 2009

Digitizing Vinyl, Part Five: Preamps

As I mentioned in one of my previous posts, the most obvious wild card in my initial efforts to digitize records was my Vestax mixer. Its a good mixer with a clean signal, but I never felt like I was hearing what was actually, ONLY recorded on the vinyl. DJ mixers do have built-in phono preamps, but they also pass everything through a gain control, an EQ, and three different volume controls. Every step of this sends the audio signal through all kinds of circuitry that can add color the audio. Even with everything set to zero, it never sounded truly neutral. In a club setting, this is no big deal, but my goal with this project is preservation and restoration, not simply jacking up the bass. So operating under the assumption that less is more, I bought a dead simple Rolls VP29 Phono Preamp... the trouble with that unit was it went too far in the other direction. Because I'm digitizing mostly older records, sometimes I do need to have access to a single volume knob to help get the signal to the sweet spot. I finally settled on the Bellari VP130 Tube Phono Preamp which had all the features I was looking for, plus the added cache of having a tube. Everything sounds better with a tube right?

The standard Party Line regarding audio is that analog is always better. It's "warmer and punchier" while digital is "cold and harsh." I'm not going to embark on a rant (8-track) about this (cassette), but I will sum up my experiences. The tube preamp I bought does two things. The first is it has much more low end response, probably between 4 and 8 dB if I had to guess. It also has a much smoother curve to the low end frequencies. The second thing I have noticed is a definite difference in the sound of the mid and high end. Sadly, I just don't know how to describe it. So I'll say this... I think the tube preamp sounds better. At the end of the day, I'm an obvious heretic who is methodically converting beloved records to digital, so I'm not a hater of the 1 and 0... But passing the signal through a tube on its way to being frozen forever on a hard drive seems to produce a pleasing result. That said, I have noticed it is easy to accidentally get slight distortion on bass drum hits and sub bass parts, so I have to be really careful with the volume knob. At which point it is probably worth offering another tip: test what you are doing. Specifically, record small sections, and play them back. It's better to use up 5 or 10 minutes double checking your settings than to record a whole side of a record and find out later you had some distortion.

While writing this, I just noticed that Bellari now makes a USB version of its tube preamp, which might be worth trying. I'll be writing about A to D converters in my next installment.